Automatic gun



A March 6, 1945. l

D. s. BELL ETAL AUTOMATIC GUN Filed March 15, 1941 3 Sheets--Sheel'l l INVENTOR S Dar/itt S. Bell l UscarRI/Vllkaner March 6, H945. D. s. BELL ErAl.

AUTOMATIC GUN Filed March l5, 1941 3 SheeiS-Shveet 2 .WAM

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I I I i I l LI March j6, 1945. D. s. BELL ETAL AUTOMATIC GUN 3 Sheets-Sheet 3 Filed March 15, 1941 INVENTORS DaT/ILISBQZZ OscaTZ. Wikander Patented Mar. 6, 1945' AUTOMATIC GUN f Davitt S. Bell and Oscar R. Wikander, Pittsburgh, Pa., assignors to Edgewater Steel Company, Oakmont, Pa., a corporation of Pennsylvania l Application March 15, 1941, Serial No. 383,538

Claims.

This invention relates to automatic guns, popularly designated as "machine guns. The characterizing feature of such guns, many types of which are well known, is that so long as the trigger remains pressed and the su'pply of ammunition continues, they continue to fire, each cartridge being automatically fed to the chamber, discharged and ejected. Ihese guns are widely used on the ground, on airplanes and elsewhere. The automaticity of their operation is obtained (in most cases) byproviding for the recoil movement of one or more of the gun elements and the coupling of such elements with the cartridge feeding and firing pin mechanism. Except in this respect, automatic guns have not generally been provided with recoil mechanisms such as are employedlon artillery. However, increasing demands for automatic'guns of heavier caliber and of higher firing rates have rendered it imperative to provide some form of recoil mechanism for the gun as a whole. It is common, for example, to mount such guns in the wings of an airplane, and the firing thereof sets up stresses and vibrations which it is desirable4 to minimize or eliminate. In use on the ground, such a mechanism is desirable because it lightens the task of the gunner and enables him to concentrate on directing the gun and to aim it more accurately.

The .recoil mechanisms heretofore provided have not been wholly satisfactory fora variety of reasons, of which perhaps the principalone is that they have slowed down the rate of firing of the gun. As above stated, the automatic action of such a gun is based upon the recoil of one or more of the elements of the gun relative to the rest of it. If the entire gun is mounted so that it has a recoil movement, ,it will be seen that very complex and, in many cases, unpredictable inertia eiects will arise. These effects have not heretofore ben satisfactorily compensated.

We have devised a recoil mechanism whichhas satisfactorily met all requirements. It is simple and compact and may be readily adapted to existing automatic guns. It does not slow down the ring rate and it functions satisfactorily over an extreme range of conditions. It is not affected by temperature changes and does not require peri odical lubrication filling with oil or other servicing. y

We also provide an improved trigger mechanism. This mechanism is placed on the mount and functions to control the firing of the gun with entire satisfaction, despite the fact that the gun is vibrating axially at a rapid rate due to recoil forces.

In the accompanying drawings illustrating present preferred embodiments of the invention,

Figure 1 is a top plan view of a gun partly broken away;

Figure 2 is a side elevation;

Figure 3 is a partial vertical section of a modified' construction, and showing the recoil mechanism in detail;

Figure 4 is a perspective view of one of the elements of the recoil mechanism;

Figure 5 is a top plan view to enlarged scale partly broken away illustrating the trigger mechanism;

Figure 6 is a vertical section thereof on the line VI--VI of Figure 5;

Figure 7 is a section on the line VII- VII of Figure 5;

Figure 8 is a vertical section throughone of the gun handles showing the adjustable trigger stop:

Figure 9 is a top plan view of the stop; and n Figure 10 is a perspective view of the firing sear.

For purposes of illustration, we have shown vour invention as applied to the Browning M--2 automatic gun, which is indicated generally by the reference character 2. This gun is provided near the muzzle end with a threaded boss 3 (see Figure 3) concentric with the barrel 4, which boss ordinarily accommodates a trunnion ring whereby the front end of the gun is secured to a mount. As hereinafter described in greater detail, we utilize this threaded boss for connecting the recoil mechanism to the gun.

In Figures 1 and 2 we have shown a mount consisting of a pair of tubular side members 5 rectangular in cross section and provided with trunnions 8 whereby they may be adjustably mounted on a sub-base, as, for example, the framework of an airplane. At its front end, each of the side members 5 is provided with a trunnion eye 'l for supporting the front end of the gun in the manner above indicated, Toward their lrear ends, the side members 5 are each provided with slotted bearing blocks 8 containing slides 9 having trunnion pins I0 integral therewith. The trunnion pins fit into eyes on a rlug Ill secured to the bottom of the gun. This construction holds the gun securely to the mount but permits axial movement of the gun relative to the mount dueto recoil and return following the recoil. At their rear ends, the side members 5 are connected together by bolts I2 and cross members I3 and M formed of sheet metal.

Figure 3 illustrates a modified form of mount in which the gun 2' is supported at the front end by a rotatable trunnion I5 and at therear by an elevating screw I6, both well known. In this case, however, the elevating screw I6 carries a slide I'I at its upper end for receiving slide blocks 9 which, like the slide blocks 9 illustrated in Figures 1 and 2, permit recoil and return movement of the gun relative to the mount.

The recoil mechanism is indicated generally'by the reference character I8. It is shown in cross section in Figure 3. As above indicated, it is se cured to the gun by being threaded onto the boss'y 3, An internally threaded sleeve I9 is provided for this purpose. At its outer end, the sleeve I9 has a shoulder which constitutes one of two opposed buttresses for a ring spring indicated generally by the reference character 2|. The spring is'contained within acase 2'2 Vwhich makes a sliding t on the sleeve I9 and is provided with bosses 23 drilled and threaded to receive trunnion bolts-24 extending through4 the .-trunnion eyes 'I inthe form of the invention shown in Figures l and 2, and through the trunnicn I5 in the form shown in Figure 3. The trunnion bolts are semi., permanently secured by atie wire 25 which prevents them from jarring loose.

In Figure,l theseveral parts of the recoil mechanism are shown in the so-called battery position. It will be knotedthat the sleeve I9 is counterbored andthat at the/bottom of thecounterbore. there is a shoulder 26 which, when the gun isin.V battery position, registers with the shoulder 20. A floating ring 2'I is interposed between these..shou1ders and the rear end of. the ring spring 2 I. The sleeve I9is also. counterbored and Vthreadedto receive a sleeve 28, a set screw 29 being provided to prevent loosening ofthe sleeve 28` from the sleeve I9. At its outer end, the sleeve 28is-`provided with aange which forms a shoulder 3U. At its outer end, the case 22` is internally threaded to accommodate a ring 3I having an inner shoulder 32. The ring 3i is held against loosening by means of a set screw .33. When the gun is in battery position, the shoulders 30 and 32 lieinthe saine: plane and av noating ring. is. interposedbetweenthem and the outer end ofthe ring. spring.

The. ringspringV isgenerally ofthe type. disclosed in. Kreissg Patent. No. 1,515,346 dated November 11, 192Land consists. oa series. of .interfitting elastic rings having. complemental tapered friction surfaces.. In the case illustrated, there. are three outer rings. 35., 36and. 3.1, these being uninterrupted annulihavingtapered inner faces to accommodate. two inner rings38.' The angle f taper on the severalv rings will, in any case, be greater than the angle of friction for the surfaces employed, and the surfaces are carefully formed and lubricated so that upon the ap plication of the requisite pressure the nest of in- -tertting rings will foreshorten smoothly.

The recoil spring isarranged. substantiallycoaxially with the barrel .of the gun, thus eliminating any eccentric` forces.

The. recoil mechanism, ,as illustrated is a complete: sub-assembly, or cartridge which may be manufactured entirely apart fromthe gun, may bejseparately shippedand handled without. danger. of misplacement or misadjustment. ofv the parts, and may be quickly fitted, to existing guns. The use of the. recoil mechanism profoundly affects the performance of the gun, making it easierto re and control, reducing wear and tear on the'airplane or other structure on which it is mounted, permitting the useof. heaviercalibers in such cases and in many cases materially increas" ing the ring rate of the gun without any other change. f

The operation ol' the recoil mechanism will now be described: Assuming the gun to be in battery position, as shown in Figure 3, and that a cartridge in the chamber is fired, there will be a recoil of the element lor velements of the gun which render its ringautomatic; but the recoil'force will be transmitted to the remainder of the gun and it will, therefore, tend also to recoil. With the combination above described,

- there will be a movement of the boss 3 and,

hence, of the sleeve I9 away from the muzzle ofthe gun, that is to say, from left to right as viewed nthe drawings. The case 22 is held against such' movement by the trunnion bolts 24, but the sleeve4 28 will move rearwardly with the sleeve I9 to which it is attached and the shoulder 3U will bear against the floating ring 34 andcompress .the ring spring'2I, thiscompression continuinguntil the rearward movement of the'gun as` a wholeis completed.. A portion ot the. energy of recoil will beabsorbed in friction (heat) in the ringspring, but sufficient will remain to causethe spring. to` refexpand. In reexpanding, it willagain .move the gun forward (right to left in the drawings) with respect to the mount. Due to inertia of the. gun, it will continue to move forward: beyond battery position. Our mechanism permitsthis. At `battery position, the shoulder. 20engages theiloating ring 21 and. compresses the spring 2 I thus building up resistance on the` overtravel. The overtravel will be very short if the spring'v is properly designed, andre-expansion of the spring will promptly return. the gun to battery position.

The characteristics ofthespring are impor tant. It should have `an energy-absorption capacity of at least 50%; thatis tosay it should be so designed thatat least 50% -of the energy imparted toit will be. rabsorbed by friction. This is found to give very satisfactory operating characteristics. Itis also desirable, that the spring be under an initial compression. This is effected by making thezspring .with afree. length greater than thedistance between the floating rings 2T and34.. The provision of an initial compression limits the .travel of the 4gun forwardly of battery position and` improves,Y the rate of nre of the gun over installations wherethere isV no substantial initialycompression. The period of the spring shouldbe shorter than-.the desired time interval betweensuccessive shots of' the gun. By the period of the spring. we mean the time required for a. natural, (free) alternation of the spring if it is compressed and then released. This aids in maintaining the desired firing rate of the gun.

.While we preferto use aring'spring for resisting the recoil of the gun, other types of energyabsorbing springs may be used. Ordinary coil springs. are not satisfactory `because they do not absorb any .energy excepta.minute..a.mount by internal friction .within the Vmetal itself when the spring is compressed orextended. This internal friction is so small that it is disregarded in spring computations and We.- do not include ordinary coil springs either of .the tension or. compression type Within the term energy-absorbing spring. ThereV are.. however, energy-absorbing springs other than thering type whichif properly designed, should give. satisfactory results, as, for example, springs wound with adjacent coilsiin section that the adjacent coils will be onone another whenA the spring is compressed and thus absorb energy by friction. Such a spring is shown in Patent No. |758,066. Other types comprise two or more rods concentrically wound and nested so that there is frictional engagement between coils. Such av spring is shown in Patent No. 2,043,566. Springs of both of the types last mentioned are well known and require no detailed description.

The trigger mechanism is illustrated generally in Figures 1 and 2 and in detail in Figures 5 to 10, inclusive. As above stated, the mount has a cross member I3 and this member carries two grips 40 and lll which may be grasped by the gunner. A trigger 42 is mounted adjacent the grip 40. The trigger is made integral with a rocker shaft 43 which is pivoted in the mount at M. The shaft 43 has an arm 45 carrying an offset nger 46 having a roller l1 thereon. The roller engages a firing sear 50 which is mounted at 5l on the gun proper andr is effective for actuating it. The sear has a surface 52 which is engaged by the roller 41, and the squeezing of the trigger serves to move the sear from its non-firing position, shown in dotted lines in Figure 6, to its firing position, shown in full lines. In the firing position, the surface 52 lies in a plane parallel with the axis of the gun, that is to say, parallel with the direction of movement of the gun on recoil and return. In consequence, the sear may move back and forth under the roller t1 as the gun recoils and returns to battery position after successive shots, but so long as the trigger is squeezed the sear is 'held in firing position. v

The movement of the trigger is limited by a rotatable stop 53 which is caried by the grip 40. The stop 53 is in the form of an eccentric ring which is loosely mounted on a reinforcing tube 54 within the grip 40. A set screw 55 holds it against rotation and in any desired position. By rotating the stop 53 and setting it with the screw 55, the proper depression of the roller M can be determined.

A safety catch 56 is provided. It is knurled or serrated for ready movement by the thumb of the gunner and works in a slot 51 formed in the cross member I3. It is connected by a set screw 58 to a pawl 59 which in the safe position is engageable with a lug 60 on the rocker shaftV 43 and prevents movement of the trigger to ring pof sition. A detent 6l holds the safety catch in either of its desired positions.

We have illustrated and described a present preferred embodiment of the invention. It will be understood, however, that this is by way of I illustration only and that the invention may be otherwise embodied or practiced within the scope of the following claims.

.We claim:

l. An automatic gun, a mount therefor, the gun being movable on the mount, the mount being so constructed and arranged as to permit of recoil and return movement of the gun on ring thereof, and a recoil mechanism operatively connected to the gun and to the mount and comprising a ring spring formed of intertting elastic rings having complemental tapered friction surfaces.

2. An automatic gun having a barrel, a mount for the gun, the gun being movable on the mount, the mount being so constructed and arranged as to permit of recoil and return movement of the gun on firing thereof, and a recoil mechanism operatively connected to 'the gun and to the mount and comprising a ring spring formed of interiitting elastic rings having complemental tapered friction surfaces, the ring spring being placed substantially coaxially with the barrel.

3. An automatic gun, a mount therefor, the gun being movable on the mount, the mount being so constructed and arranged as'to permit of recoil and return movement of the gun on firing thereof, and a recoil mechanism operatively connected to the gun and to the mount and comprising a ring spring formed of intertting elastic rings having complemental tapered friction surfaces, the spring having an energy-absorption capacity of at least fty per cent as herein defined.

4. An automatic gun, a mount therefor, the gun being movable on the mount, the mount being so constructed and arranged as -to permit of recoil and return movement of the gun on firing thereof, and a recoil mechanism operatively connected to the gun and to the mount and comprising an energy-absorbing spring having complemental friction surfaces.

5. An automatic gun having a barrel, a, mount for the gun, the gun being movable on the mount, the mount being so constructed and arranged as to permit of recoil and return movement of the gun 'on firing thereof, and a recoil mechanism operatively connected to the gun and to the mount and comprising an energy-absorbing spring having complemental friction surfaces. the spring being placed substantially co-axially with the barrel.

6. An automatic gun, a mount therefor, the gun being movable on the mount, the mount being so constructed and arranged as to permit of recoil and return movement of the gun on firing thereof, and a recoil mechanism operatively connected to the gun and to the mount and comprising an energy-absorbing spring having complemental friction surfaces, the spring having an energy-absorption capacity of at least fifty per cent as herein defined.

7. An automatic gun, a mount therefor, the gun being movable on the mount, the mount being so constructed and arranged as to permit of recoil and return movement of the gun on firing thereof, and a recoil mechanism operatively connected to the gun and to the mount and comprising an energy-absorbing spring having complemental friction surfaces, the spring having a period less than the time interval between successive shots from the gun.

3. An automatic gun, a mount therefor, the gun being movable on the mount, the mount being so constructed and arranged as to permit of recoil and return movement of the gun on firing thereof, and a recoil mechanism operatively connected to the gun and to the mount and comprising an energy-absorbing spring having complemental friction surfaces, the spring being under an initial compression.

9. An automatic lgun, a mount therefor, the gun being movable on the mount, the mount being so constructed and arranged as to permit of recoil and return movement of the gun on firing thereof, a recoil mechanism comprising an energy-absorbing spring having complemental friction surfaces, a case holding the spring under an initial compression. the case being secured to the mount, and two buttresses connected to the gun and respectively engageable with the opposite ends of the spring and effective for compressing the same, one upon rearvgard movement of the gun from battery position, and the other upon forward movement of the gun from such position.

10. An automatic gun, a mount therefor, the

recoilv mechanism comprising an energy-absorbf ing spring, and a pair of movable buttresses operatively engaging the spring at its opposite ends and effective upon relative movement for transmtting energy to and fromthespring, the buttressesbeing soarranged as to be movable, one upon rearward movement of the gurlV from bat-` tery position, and the other uponforward'move- :3 ment ofthe gun from such position.

DAVITT S. BELL. OSCAR R. WIKANDER. 

